Atypical Presentation of Synovial Osteochondromatosis at the Subtalar Joint Mimicking a Fracture Following Trauma: a Case Report

ISSN: 2574-1241 Volume 5- Issue 4: 2018 DOI: 10.26717/BJSTR.2019.13.002341 Juzaily Fekry Leong. Biomed J Sci & Tech Res

Case Report Open Access

Atypical Presentation of Synovial Osteochondromatosis At the Subtalar Joint Mimicking A Fracture Following Trauma: A Case Report

Azammuddin A, Tan JA, Othman MS, Hanif KAA, Halim MAHA and Leong JF* Department of Orthopaedics, Tuanku Jaafar Hospital, Malaysia

Received: : December 10, 2018; Published: : January 10, 2019 *Corresponding author: Juzaily Fekry Leong, Department of Orthopaedic and Traumatology, Malaysia

Abstract Synovial osteo chondromatosis (SOC) are benign tumors arising from metaplastic synovial tissue of joints, bursae or tendon sheath. These tumors are most commonly found in the knee joint and rarely presents in the foot and ankle region. We report a case of a middle age gentleman with primary SOC and was misdiagnosed as an acute neck of talus fracture following trauma. He presented with pain one week after a fall and examination revealed a 4x4 cm bony hard swelling over the anterolateral aspect of the right ankle joint. Radiograph showed a possible neck of talus fracture but Computer Tomographic (CT) scan revealed no fracture but bony mass within the sinus tarsi and extending to the lateral aspect of the ankle joint.

the rarity of SOC in the foot and ankle region, which mimicked a fracture of the neck of talus. Excision biopsy confirmed SOC and patient recovered fully without any pain and no sign of recurrence after 1-year follow-up. This case highlights Keywords: Chondromatosis; Subtalar joint; Synovial

Abbreviations: SOC: Synovial Osteo Chondromatosis; MRI: Magnetic Resonance Imaging; HPE: Histopathology Examination

Introduction over the ankle region prior to the above injury. On examination, Synovial osteo chondromatosis (SOC) are benign tumors arising there is a localized swelling just anterior to the lateral malleolus. from synovial tissue of joints, bursae or tendon sheath. These synovial tissues undergo metaplasia to form cartilaginous or aggravated with passive inversion and eversion of the subtalar osteocartilaginous bodies which may break off from the synovial On palpation it was tender and firm in consistency. The pain was joint. The ankle was otherwise stable. All bloods investigations surface, causing pain or mechanical blockage to the joint [1]. were normal. Radiographs of the right ankle showed a large Involvement is usually monoarticular, with the large joints being most frequently affected. The knee joint is involved in 60 to 70% to the subtalar joint. From the lateral view, there appeared to be a of cases; the shoulder, elbow, and hip are the next most frequently calcified mass that contained multiple radiopaque bodies, lateral suspicious fracture line traversing the neck of talus (Figure 1). As involved joint. It rarely involves the joints of the foot and ankle we were unable to rule out a fracture, we proceeded with a CT scan region [2]. Here we report an atypical presentation of primary SOC of the right ankle that reported no obvious fracture but revealed of the right subtalar joint in a middle age gentleman, who presented a large bony mass measuring 5x4x4 cm within the sinus tarsi and with pain of the right ankle and was misdiagnosed as a right talus extending to the lateral aspect of the ankle joint (Figure 2). fracture, after a traumatic fall in his workplace. In view of the benign presentation of the tumor an excision Case Report biopsy was performed. The surgery was done through anterolateral A 40-year-old male was referred to our Orthopedic Department approach to the talus, exposing the whitish bony hard mass that with a history of trivial fall one week ago in his workplace and was diagnosed as a right neck of talus fracture. It is associated with showed a solitary whitish bony tumor measuring about 5x4x4 cm was sitting in the region of the sinus tarsi. Intraoperative findings pain and limited range motion of the affected ankle especially on in size (Figure 3a), which was encased by hypertrophied synovium. eversion and inversion of ankle. He denied any pain or swelling The disease was noted to have eroded the adjacent plantar surface

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of the talar neck. The tumor was removed as a whole and sent consistent with synovial chondromatosis. No nuclear atypia was for histopathology examination (HPE). The section showed few seen, ruling out malignancy (Figure 3b). chondorocytes arranged in lobules within the synovial which was

Figure 1: a) AP view of the right ankle showing a calcific mass (arrow) that appears to be in continuity with the subtalar joint. b) Lateral view of the right ankle showing multi-lobulated calcified mass overlapping the talus with a mistaken fracture line at the neck of talus (arrow).

Figure 2: Mid-coronal view of the CT scan showing a bony mass (arrow) arising from the sinus tarsi of the right ankle joint, extending laterally.

Figure 3: a) Gross specimen of the glossy white osteocartilaginous tumor which was encased by hypertrophied synovium. b) Section from tissue showed clusters of chondrocytes (arrow) arranged in lobules consistent with diagnosis of SOC, without cellular atypia, ruling out malignancy.

Cite this article: Azammuddin A, Tan JA, Othman MS, Hanif KAA, Halim MAHA, Leong JF. Atypical Presentation of Synovial Osteochondromatosis At the Subtalar Joint Mimicking A Fracture Following Trauma: A Case Report. Biomed J Sci & Tech Res 13(1)-2019. BJSTR. MS.ID.002341. DOI: 9700 10.26717/ BJSTR.2019.13.002341. Biomedical Journal of Scientific & Technical Research Volume 13- Issue 1: 2019

Post operatively the patient’s ankle was immobilized with Treatment of patients with SOC are tailored according to a below knee backslab for 2 weeks for pain management. After their presenting symptoms. Asymptomatic patients do not require 2 weeks, he was allowed full weight bearing and referred to the surgical management and mere observation with regular follow-ups physiotherapist for interferential and isometric therapy to achieve full range of movement and functional outcome of the affected symptoms, surgical management may be offered. The traditional would be sufficient. In patients presenting with pain, or mechanical ankle [3]. Patient was followed up for 1 year post-operatively and surgical approach is an open arthrotomy of the joint with removal of was ambulating normally without pain. There were also no clinical all loose bodies with extensive synovectomy. Recent advancements or radiographic evidence of recurrence. have enabled these loose bodies to be removed arthroscopically [6]. In the present case, open surgery was performed due to its large Discussion size and tightness of the subtalar joint. The exact prevalence of SOC is unknown, but the disorder is Patients with SOC must also be counselled regarding the risk of rare worldwide. Occurrence are more common among males age recurrence. The recurrence risk after surgical removal are variable between 20-40 years, and only a few case reports have described the ranging from 3.2% to 22.3% [7]. In the above patient, there was no condition occurring in children [4]. It commonly occurs in synovial evidence of recurrence in six months post-operatively, but longer joints including the knee, hip and shoulder. However, it is rarely seen follow-up must be done in case of future recurrence. in the foot and ankle region [2]. SOC may be divided into primary and secondary forms. Primary SOC differs from its secondary Conclusion counterpart as it occurs in an apparent normal joint whereas Primary SOC even though rare in the foot and ankle region, secondary SOC develops in patients with pre-existing arthritis [5]. must be taken into consideration in patients presenting with The pathogenesis of SOC can be divided into three stages. In stage slow growing benign bony mass over the mentioned joint. one, there is only active synovial disease without presence of loose Surgical excision offers good functional outcome with low rates of bodies. Stage two disease would include formation of loose bodies recurrence. on top of active synovial disease and stage three would only have loose bodies without evidence of synovial disease. In our patient, References the SOC was in stage two as evident by the bony tumor being 1. Kirchhoff C, Buhmann S, Braunstein V, Weiler V, Mutschler W, et al. encased by hypertrophied synovium after excision biopsy. (2008) Synovial chondromatosis of the long biceps tendon sheath in a child: a case report and review of the literature. J Shoulder Elbow Surg Patients usually present with a palpable nodule, mono-articular 17(3): e6-e10. pain, swelling, stiffness with or without mechanical symptoms 2. Kerimoglu S, Aynaci O, Saraçoglu M, Cobanoglu U (2008) Synovial of the joint involved. On examination of the joint, there may be chondromatosis of the subtalar joint: a case report and review of the effusion, non-tender palpable mass with reduction of the range of literature. J Am Podiatr Med Assoc 98(4): 318-321. motion. The blood investigations are normal and plain radiographs 3. Pallavi B, Vaishali J, Devi TP (2017) Effect of circuit training in osteoarthritis of the knee. Asian J Pharm Clin Res 10: 333-335.

Secondary widening of the joints space may also be noted. CT scan is 4. Wodajo F, Gannon F, Murphey M (2010) Visual Guide to Musculoskeletal show large nodules with stippled or ring like calcified opacities. Tumors: A Clinical – Radiologic – Histologic Approach. Saunders.

5. Lin YC, Goldsmith JD, Gebhardt MG, Wu JS (2014) Bursal synovial useful to detect calcified intra-articular loose bodies, bony erosions a plain radiograph. In cases like the above, a CT scan would also be chondromatosis formation following osteochondroma resection. and the real extent of the lesion, which are difficult to assess using Skeletal Radiol 43(7): 997-1000. useful to exclude the diagnosis of a fracture. Magnetic resonance imaging (MRI) is useful to evaluate the status of the ligaments and 6. Doral MN, Uzumcugil A, Bozkurt M, Atay OA, Cil A, et al. (2007) Arthroscopic treatment of synovial chondromatosis of the ankle. J Foot adjacent articular cartilage especially when the disease is at its Ankle Surg 46: 192-195. early stages. Tissue biopsy remains the gold standard of diagnosis Davis R, Hamilton A, Biggart JD (1998) Primary synovial chondromatosis: and will provide useful information to exclude other differential 7. A clinicopathologic review and assessment of malignant potential. diagnosis especially malignant conditions [4]. Human Pathology 29(7): 683-688.

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